Three local government Web sites in Wales have admitted to receiving simultaneous hacking attempts in the last week.

The official Web sites of Carmarthenshire County Council, Pembrokeshire County Council and the town of Abergavenny were all compromised this week when hackers broke into the servers and attempted to deface the sites' homepages.

The cyber-attacks have prompted criticism that local authority Web sites need to have stricter security measures in place. The Welsh Local Government Association has received three unsuccessful hack attempts to its Web site in the last three months, and is now warning public organisations to improve Web site security or suffer more sabotage.

Carmarthenshire County Council was the worst affected when an obscene message was posted on its homepage. "We would like to reassure our customers that no confidential information was affected by this breach of security," said a spokeswoman for the Council. "We have totally reviewed our security measures to ensure that such an incident doesn't happen again."

Details of the hacker's message is not being disclosed, but the spokeswoman claims that the defacement was noticed within the hour. The homepage has now been restored to normal.

Pembrokeshire County Council was more fortunate -- its server was successfully hacked, but the site itself was not defaced. "The hackers didn't so any damage, and no message was left on the site," confirmed a spokesman at the council.

Abergavenny's official town Web site has also been defaced with obscene messages this week.